ABC/2

ABC/2 is a fast and simple method for estimating the volume of intracerebral hemorrhage (or any other ellipsoid lesion for that matter) which does not require volumetric 3D analysis or software. Intracerebral hemorrhage volume is an important predictor of morbidity and mortality (and thus trial eligibility) which is often under-reported 1. It has been well-validated and correlates highly with volumes calculated by planimetric techniques 2,3.

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Formula

First described by Kwak et al. 4 and popularised by Kothari et al. 2:

A x B x C / 2

A = greatest hemorrhage diameter in the axial plane

B = hemorrhage diameter at 90º to A in the axial plane

C = originally described as the number of CT slices with hemorrhage multiplied by the slice thickness, but can simply be substituted with the craniocaudal diameter of the hemorrhage where there is access to multiplanar reformats 1

If the measurements are made in centimetres (cm), then the volume will be in cubic centimetres (cm3).

Mathematical basis

The above formula is a simplified version of the formula for the volume of an ellipsoid, which is: